The invention relates to a roller for an image forming apparatus such as a platen roller, and to a mold for forming such a roller.
For example, a wire dot printer forms desired characters and graphics on a recording sheet by impinging the tips of wires onto the recording sheet through an ink ribbon. As a result of this operation, there exists the problem that impinging noise is made during data writing.
In order to overcome this problem, the present applicant has proposed a platen roller in Unexamined Japanese Patent Publication No. Sho. 63-256470. Unlike a platen roller that has heretofore been constructed of a hollow metal pipe, the proposed platen roller is characterized by charging air-bubble-containing concrete into such hollow pipe. As a result of this construction, the propagation of noise is controlled to implement low noise design. On the other hand, this platen roller imposes difficulties in molding the roller shaft with correct shaft center ensured, as well as the problem of noise absorption, durability, and the like.